Defect mediated exchange bias in oriented (111) Fe3O4/(100) GaAs

Bhat, Shwetha G.; Kumar, P. S. Anil

doi:10.1016/j.tsf.2016.11.022

Cited by 4 publications

(2 citation statements)

References 36 publications

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“…These conditions impose a unidirectional magnetic anisotropy on the system, which characteristically increases the coercive field (H C ) and horizontally offsets the origin of the hysteresis curve by an amount defined as the EB field (H EB ). The functionality of the FM/AF interface is often modified by complex chemical structures, such as: incommensurate growth parameters, alloying, lattice mismatch, layer roughness and/or interdiffusion of atoms across the interface [8][9][10][11][12]. For this reason, it would be highly desirable to lift the structural constraints of the interface to enable a consideration, purely, of the magnetic exchange across it.…”

Section: Introductionmentioning

confidence: 99%

Tailoring exchange bias in ferro/antiferromagnetic FePt₃ bilayers created by He⁺ beams

Causer

Zhu

Ionescu

et al. 2018

J. Phys.: Condens. Matter

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We report on artificial exchange bias created in a continuous epitaxial FePt film by introducing chemical disorder using a He beam, which features tailorable exchange bias strength through post-irradiation annealing. By design, the ferromagnetic (FM)/antiferromagnetic (AF) heterostructure exhibits stratified degrees of chemical order; however, the chemical composition and stoichiometry are invariant throughout the film volume. This uniquely allows for a consideration purely of the magnetic exchange across the FM/AF interface without the added hindrance of structural boundary parameters which inherently affect exchange bias quality. Annealing at 840 K results in the strongest exchange biased system, which displays a cross-sectional morphology of fine (<10 nm) domain structure composed of both of chemically ordered and chemically disordered domains. A magnetic model developed from fitting the characteristic polarised neutron reflectometry spectral features reveals that dual interactions can be attributed to the observed exchange bias: magnetic coupling at the FM/AF interface and also between neighbouring FM (chemically disordered) and AF (chemically ordered) domains within the nominally FM layer. Our results indicate that exchange bias is hindered at interfaces which are both chemically and magnetically perfect, while annealing can be used to balance the volume proportions of interfacial FM and AF domains to enhance the magnetic interface roughness for customisable exchange bias in mono-stoichiometric FM/AF heterostructures crafted by ion beams.

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Section: Introductionmentioning

confidence: 99%

Tailoring exchange bias in ferro/antiferromagnetic FePt₃ bilayers created by He⁺ beams

Causer

Zhu

Ionescu

et al. 2018

J. Phys.: Condens. Matter

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show abstract

“…[8][9][10][11][12]. On the other hand, structural defects can induce or modify EB by introducing moment pinning centers in the system, leading to local alteration in magnetic exchange and anisotropy [1,2,[13][14][15]. In the present work, we plan to investigate the EB effect in Sm 2 NiMnO 6 /BaTiO 3 /Sm 2 NiMnO 6 (SBS) heterostructure.…”

mentioning

confidence: 99%

Exchange bias in Sm$ _{2} $NiMnO$ _{6}$/BaTiO$ _{3}$ ferromagnetic-diamagnetic heterostructure thin films

Majumder¹,

Chowdhury²,

De³

et al. 2022

Preprint

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Exchange bias (EB) shifts are commonly reported for the ferromagnetic (FM)/antiferromagnetic (AFM) bilayer systems. While stoichiometric ordered Sm 2 NiMnO 6 (SNMO) and BaTiO 3 (BTO) are known to possesses FM and diamagnetic orderings respectively, here we have demonstrated the cooling field dependent EB and training effects in epitaxial SNMO/BTO/SNMO (SBS) heterostructure thin films. The polarized Raman spectroscopy and magnetometric studies reveal the presence of anti-site cation disorders in background of ordered lattice in SNMO layers, which introduces Ni-O-Ni or Mn-O-Mn local AFM interactions in long range Ni-O-Mn FM ordered host matrix. We have also presented growth direction manipulation of the degree of cation disorders in the SNMO system. Polarization dependent X-ray absorption measurements, duly combined with configuration interaction simulations suggest charge transfer from Ni/Mn 3d to Ti 3d orbitals through O 2p orbitals across the SNMO/BTO (SB) interfaces, which can induce magnetism in the BTO spacer layer. The observed exchange bias in SBS heterostructures is discussed considering the pinning of moments due to exchange coupling at SB (or BTO/SNMO) sandwich interface.The exchange bias (EB) phenomenon, described as the shift of isothermal magnetic hyteresis loop in the magnetic field scale, is attributed to unidirectional anisotropy effect [1,2].Ideally an antiferromagnetic (AFM) system possess equivalent energies for the two oppositely aligned magnetic sublattices. Now, the EB effect can be understood considering the exchange coupling of any one AFM sublattice spins with adjacent ferromagnetic (FM) spin arrangements, when the FM/AFM interface system (FM T C > AFM T N

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Crystallite size dependent exchange bias in MgFe2O4 thin films on Si(100)

Mallick

Kumar

2018

Journal of Applied Physics

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Single phase materials showing large Exchange Bias (EB) at elevated temperatures are highly desirable for their technological advantage. However, the fundamental interactions leading to the effect are often very complex and ill-understood. Here, we report the observation of EB in single phase (111) oriented MgFe2O4(MFO) thin films on MgO buffered Si(100). The effect is seen to persist till a significantly higher temperature of 110 K. Measurements on stoichiometric powder MFO showed the absence of EB, lower coercivity, and an enhanced saturation magnetization in comparison to thin films. This suggests the modified exchange interaction in the thin films possibly due to the presence of growth induced magnetic and structural disorder. Investigation on the nature of this EB produced some results which are akin to a conventional FM/AFM coupled system like the training effect. However, the same could not explain the observed variation in coercivity and the exchange bias field with temperature and cooling fields. We propose the existence of a disordered layer with random spin orientations at the crystalline grain boundaries of our film, promoting the AFM interaction between the ordered ferrimagnetic grains once field cooled below the spin freezing temperature. This generates a unidirectional anisotropy along the field direction which manifests as a loop shift in hysteresis measurements. A further study shows that the EB field can be varied systematically by changing the thickness of the thin films. This indicates a simple way to tune the disorder for achieving desirable magnetic properties in single phase magnetic thin films.

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Defect mediated exchange bias in oriented (111) Fe3O4/(100) GaAs

Cited by 4 publications

References 36 publications

Tailoring exchange bias in ferro/antiferromagnetic FePt₃ bilayers created by He⁺ beams

Tailoring exchange bias in ferro/antiferromagnetic FePt₃ bilayers created by He⁺ beams

Exchange bias in Sm$ _{2} $NiMnO$ _{6}$/BaTiO$ _{3}$ ferromagnetic-diamagnetic heterostructure thin films

Crystallite size dependent exchange bias in MgFe2O4 thin films on Si(100)

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Defect mediated exchange bias in oriented (111) Fe3O4/(100) GaAs

Cited by 4 publications

References 36 publications

Tailoring exchange bias in ferro/antiferromagnetic FePt3 bilayers created by He+ beams

Tailoring exchange bias in ferro/antiferromagnetic FePt3 bilayers created by He+ beams

Exchange bias in Sm$ _{2} $NiMnO$ _{6}$/BaTiO$ _{3}$ ferromagnetic-diamagnetic heterostructure thin films

Crystallite size dependent exchange bias in MgFe2O4 thin films on Si(100)

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Tailoring exchange bias in ferro/antiferromagnetic FePt₃ bilayers created by He⁺ beams

Tailoring exchange bias in ferro/antiferromagnetic FePt₃ bilayers created by He⁺ beams